As applied specifically to measurement of road surface profile, a variety of transducers or sensors have heretofore been proposed for measuring the distance between the road surface and a vehicle frame of reference driven thereover. For example, Spangler et al U.S. Pat. No. 3,266,302 employs a potentiometer carried by a trailer and responsive to movement of the trailer suspension system with respect to the trailer frame as the trailer is drawn over the road surface in question. This distance signal is combined in Spangler et al with the twice-integrated output of an accelerometer carried by the trailer for providing an overall measurement of road profile. Non-contact sensors, such as ultrasonic sensors, have been proposed for replacement of the potentiometer in the basic Spangler et al system, but have not appreciably improved the reliability and accuracy of the frame-surface distance measurement.
One important object of the present invention, therefore, is to provide a non-contact sensing apparatus, system and method which finds particular utility in the measurement of road profile, and which is adapted for improved reliability and accuracy as compared with comparable systems and methods of the prior art.
A more general object of the invention is to provide non-contact distance measuring apparatus, systems and/or methods which embody improved economy, reliability and accuracy in assembly and use. In furtherance of the foregoing, a more specific object of the invention is to provide an improved electro-optical scanner and system for measuring the profile of a relatively moving surface.